Conventionally, a power converter using an IGBT (Insulated Gate Bipolar Transistor) that is a voltage drive semiconductor element is known (for example, WO 2013-157086 A1). In such a power converter, a switching arm is usually configured by serially connecting two IGBTs.
In each of the two IGBTs that configure the switching arm, in order to suppress increase of a current flowing in the IGBTs when the IGBTs become on states at the same time, a clamp circuit configured by a series circuit of a diode and a capacitor is connected to between a gate that is a control electrode of the IGBT and an emitter that is a low-voltage-side electrode of the IGBT.
The clamp circuit suppresses increase of a gate voltage Vge by charging in the capacitor a part of a current flowing into the gate through feedback capacitance between a collector that is a high-voltage-side electrode of the IGBT and the gate. The diode is inserted so as to prevent charges in the capacitor from flowing back to the gate. The diode suppresses fluctuation of the gate voltage when a PWM signal is applied to the gate of the IGBT.